fix: resolve critical pagination bugs and add comprehensive testing

- Fix off-by-one error in pagination loop (< to <=) that prevented fetching last page
- Add Math.ceil() to maxNumberOfPages calculation for proper limit handling
- Replace hardcoded 2000 limit with configurable getMaxArtifactListCount()
- Add pagination test for multi-page artifact listing
- Add environment variable test for ACTIONS_ARTIFACT_MAX_ARTIFACT_COUNT
- Add comprehensive test coverage for getMaxArtifactListCount() function

Fixes compound bug where pagination and limit logic capped results at 900 artifacts instead of intended 1000.

packages/artifact/src/internal/shared/config.ts

@@ -97,3 +97,22 @@ export function getUploadChunkTimeout(): number {
 
   return timeout
 }
+
+// This value can be changed with ACTIONS_ARTIFACT_MAX_ARTIFACT_COUNT variable.
+// Defaults to 1000 as a safeguard for rate limiting.
+export function getMaxArtifactListCount(): number {
+  const maxCountVar = process.env['ACTIONS_ARTIFACT_MAX_ARTIFACT_COUNT']
+  if (!maxCountVar) {
+    return 1000
+  }
+
+  const maxCount = parseInt(maxCountVar)
+  if (isNaN(maxCount) || maxCount < 1) {
+    throw new Error(
+      'Invalid value set for ACTIONS_ARTIFACT_MAX_ARTIFACT_COUNT env variable'
+    )
+  }
+
+  return maxCount
+}
+